Thread-cutting mechanism for sewing machines



Jan. 5, 1932. A. R. WOOD THREAD CUTTING MECHANISM FOR SEWING MACHINES Filed Sept. 10, 1929' 5 Sheets-Sheet 1 II I 11111 Alfi'ed H. W096i Jan. 5, 1932. A. R. WOOD 1,839,823

THREADCUTTING MECHANISM FOR SEWING MACHINES Filed Sept. 10, 1929 5 Sheets-Sheet 2 l-uu j I F 5-55; mmununnmnuu uuuuuuunl 1" 5 iiim' 3mm $1, W J w v dcmm Jan. 5, 1932,

A. R. WOOD 1,839,823

THREAD CUTTING MECHANISM FOR SEWING MACHINES 5 Sheets-Sheet 3 Filed Sept. 10, 1929 Jan. 5, 1932. A. R. WOOD 1,839,823

THREAD CUTTING MECHANISM FOR SEWING MACHINES Filed Sept. 10, 1929 5 Sheets-Sheet 4 i 3 M I N a (Q i i z Q} L A: N S "a m N j g gwwntoz Jan.- 5, 1932. A. R. WOOD THREAD CUTTING MECHANISM FOR SEWING MACHINES Filed Sept. 10, 1929 5 Sheets-Sheet 5 gwomdoz Alfi wd 153. 7150i daemon buttonhole is completely stitched.

Patented Jan. 5, 1932 airs srATEs PATENT," OFFICE I ALFRED n. WOOD, 0F,BRIDGEPOR'LCONNECTICUT, ASSIGNOR TO THE srnenn mire.

FACTURII TG COMPANY, OF,ELIZABETE, NEW JERSEY, A CORPORATION OF NE? 7 JERSEY THREAD-CUTTING MECHANISM FOR SEWING MACHINES Application filed September 10, 1929. Serial No. 381,589;

This invention relates to buttonhole sewing machines, and has for an object to provide a machine of this type witha threadcutter which not only will cut the needlethread close to; the work at the end of a seW- ing operation and hold the beginning end of the needle-thread for the beginning of'the nextsewing operation, but also will'retrim the beginning end of the needle-thread close to the work, so that both ends of the needlethread will beuniformly trimmed.

In buttonhole sewing machines,it is customary-to provide the upper-member or foot of the work-clamp with av thread-cutting and nipping blade which is actuated at the end ofa stitching period to cut and nip the needle-thread. Thisthread-cutting and nipping blade holds the beginning end ofthe needle-thread during the sewing of the first side and end of the buttonhole. As the sew:

ing proceeds along the second or return side of the but-tonhole and nears the starting point, this blade is retracted to get it in readiness to cut the needle-thread after the When the blade is retracted, however, it releases the beginning end of the needle thread which is in a position to be sewed-in or bound down by the final stitches of the buttonhole. There is a certain lack of uniformity in the product of such a machine, however,due to the fact that the beginning thread endis not disposed of with certainty and may at times protrude to an unsightly extent necessitating hand retrimming.

According to the present improvement, provision is made for operating the threadcutting and nipping blade twice for eachfb-utton hole producing cycle, once before the sewing is completed, preferably just after the side and end stitches are made, when it is safe to release the beginning end ofthe needle-thread, and a second time afterthe sewing iscom'ple'ted; The first operation of the blade retrims the beginning end of the needle-thread and the second operation trims the finishingend'of the needle-thread; both ends being thus uniformly trimmed closeto thework. Y In the accompanying drawings, Fig. 1 is a side elevation of a buttonhole sewing machme embodying the invention. Fig. 2 is a reverse side elevation of the machine. Fig.

3 is a horizontal section through the bracketarm standard, showing the machine-bed plan. Fig. 4 is a plan view of the threadcutter actuating mechanism shown in Fig. 3', at its first active period in the sewing operation.- Fig. 5 is a rear end elevation of the machine. Fig. 6 is a'sectionon theline 66, Fig. 1. Fig. 7 .is abottom plan view of the machine. Fig. 8 is a sectional view of the thread-cutter showing the beginning thread-end nipped preparatory to the sew ing operation. Fig. 9 shows the beginning thread-end held nipped. after the sewing is started. Fig. 10 shows the release of the thread-end after the first barring stitches are formed, andFig. 11 shows the retrimming of the beginning thread-end which takes place immediately after the thread-end is released.

In the preferred embodiment of the inventionillustrated 1 represents the bedof a straight buttonhole sewing machine having a standard 2and overhanging bracket-arm 3 terminating in the head 4 in which is mounted on the pins 5 a gate 6 carrying the reciprocating and laterally vibrating needle bar 7 carrying the eye-pointedneedle 8. The needle-' bar 7 is actuated by suitable connections from the main-shaft 9,.the period of action of which is controlled by a stop-motion device 10. The needle-bar actuating mechanism is preferably constructed substantially in accordance with the disclosure of the copending application ofE. B. Allen, Serial No. 367,511, filed May 31, 1929. I

-The stop-motion device is preferably constructed substantially in accordance with the disclosure of the copending application of E. B. Allen and W. Myers, Serial No. 272,416, filed Apr. 24, 1928. It comprises a tilting stop-motion lever pivoted at lland carrying the spring-pressed plunger 12 which, when 21 fixed to the rock shaft 22.

' rearwardl over such arm. When the al-u'n er plunger 12 is depressed by the eccentric portion 14 of the stop-cam, the arm 18 is carried below the plunger 19 which is then projected 12 is projected upwardly by the spring 15 into the stop-notch 16, the arm 18 lifts'the J 3 plunger 19 and thereby gives a rocking impulse to the shaft 22 for a purpose to be de' scribed. V i j 1 V The needle 8 cooperates with the usual oscillating shuttle 23 to form a lock-stitch button- V nal and lateral feed-cam grooves, 29 and '30,

hole seam. The-shuttle-thread tension is preferably adjusted to run loose and the needle-thread tension is tight, so that the shut tle-thread loops will be drawn to the upper side of the work by the needle-thread which willlie wholly on the upper side ofthe work and extend in substantially a straight line through the loops of shuttle-thread ;'this type of seam being known asa lock-stitch purled buttonhole seam. I

iThe work-clamp is: of the well known con-V struction comprising the longitudinal slide plate 24 mounted-in ways 25 in the cross-slide plate 26 which slides in ways 27 transversely of the bed 1. The slide-plates 24,26 are actuated by the usual connections withlthe feedwheel 28 in which ar'e cut the usuallongiudirespectively. The'longitudinal slide-plate 24 forms the lower element of the worleclamp and has pivotally mounted thereon at 31 the upper clamp-lever 32 carrying the universally tiltable clamping foot 33 in which is mounted on the vertical shaft 34-, the usual'thread cutting and nipping blades 35, 36, such as shown in the Allen Patent, No. 885,310, of April 21, 1908. The shaft 34 has fixed to its upper end a crank-arm 37 to which is pivotally connected a rod 38 slidably supported by the guidebracket 39 mounted on the clamp-lever 32. A spring 40 urges the blades 35, 36 to closed or thread-cutting and nipping position, with thestop-collar 41 in engagement with the bracket 39, as shown in Fig; 3.

The stop'motion operated rock-shaft 22' carries at itsforward end an "arm 42,:011 whichis pivoted at 43 asprlng-pressed extension 44 which, in the initial position of the a parts, yieldingly rests upon the rod 38, as shown in dotted lines in Figs. '3 and 6; When the machine'is sewing down the first'side of the buttonhole,-the forward movement ofthe work-clampcarries the end of the rod 38' beyond the latch-extension 44 which is immediately swung downwardly by its spring into the path of'the rod-'38. In the return moveiVhen. the 1 ment of the work-clamp, in sewing the second side of the buttonhole, the end of the rod 38 strikes the latch extension 44 and the continued rearward movement of the workclamp causes the thread-cutting and nipping blades to be opened, in which position the blades are held by the extension 44 when the final stitches are being made. When the stop-motion device is'trip'ped, the rocking motion imparted to the shaft 22 by the upward motion of the stop-plunger 12, lifts the latch-'extension44 above the end of the rod 38, thereby releasing such rod which is immediately drawn rearwardly' by the spring 40 to close the blades 35, 36. The operation so far described is the usual operation of the parts in question, as disclosed in said Allen PatentNo. 885,310.

The nipped or beginning end of the needlethread is rather long and, under the old method of operation, is released and allowed to stand in the way of the formation of the final barring-stitches which are superposed upon the initial stitches, with the result that this long beginning end of thread is in a position to be crumpled down below the path of the thread-cutter so that it is not retrimmed by the thread-cutter in its action in severing the finishingend of the needle-thread, and

{pars the appearance of the finished buttonore.

According to the preferred embodiment of the invention, means are provided for operating" the thread cutter twice per buttonhole producing'cycle, once at the end of the sewing of the first side and bar of the buttonhole and again, as usual, at the end of the sewing of the second side and finalbar of the buttonholeQ The first operation of the threadcutter releases and retrims the beginning end of the. needle-thread before there is any danger that it will be displaced from or crumpled below the path of thethread-cutter by supel posed stitches. To this end there is fixed to the'usual feed cam shaft 45 a disk 46 formed with timing holes 47 one of which is entered by a'pin 48 on the cam 49 loosely mounted on the shaft 45 and yieldingly pressed upon the disk 46 by the spring 50. The cam 49 may be lifted by its knurled hub 51 and turned relative to the shaft 45 to enter the pin 48 in a selected one of the holes 47 The cam 49 engages the lever 52 which is pivoted at 53 on the bracket-plate 54 screwed to the bed 1. The lever 52 is connected by the link 55 to the lever 56 pivoted at 57 to the bracket-plate 54. The lever 56 has an upturned end 58 arranged to engage the block 59 secured to the thread-cutter. operating rod 38 and push the rod 38 forwardly to open the thread-cutter When the point of the cam 49 passes the lever 52, the rod 38 is suddenly released and the thread-cutter closes upon and retrims the beginning endof the needle-thread. The cam 49 is preferably so timed that the beginning end of the needlethread will be held nipped until after the first barring stitches are formed, after which such end is released and retrimmed early in the sewing of the second or return side of the buttonhole.

When the machine is started, the beginning end a of the needle-thread is held nipped as shown in Fig. 8. The sewing begins at b, Fig. 9, and continues down the first side of the buttonhole with the end (1 held nipped until after the first barring stitches 0, Fig. 10, are formed, whereupon the blades 35, 36 are opened to release the end a of needle-thread. The first opening of the blades 35, 36 is immediately followed by their closing movement, Fig. 11, which retrims the beginning end of needle-thread, leaving the short end The sewing continues down the return side of the buttonhole and a second opening of the blades 35, 36 occurs as the travel of thework-clamp carries the end of the rod 38 against the latch extension l of the lever 42, as previously described. When the stop-motion device is tripped at the completion ofthe sewing of the buttonhole by the usual engagement of the tripping point on the feed-wheel 28 with the usual stop-motion release latch-lever 61, the blades 35,36 close;

and trim the finishing end of needle-thread; holding the thread-end extending to the needle in readiness for the next sewing operation, as shown in Fig. 8.

The feed-shaft 45 makes'one rotation per buttonhole producing cycle and'is preferably driven through suitable gear-connections 62 with an intermediate shaft 63 having a pin and star-wheel driven connection 6% with the main-shaft 9, as described in the Allen and Myers application, Serial No. 272,416, previously referred to.. The patent to Allen, No. 1,629,139, of May 17, 1927, discloses a feed'wheel and teed-wheel driving mechanism such as is used in the present machine.

-While the invention is shown and described as embodied'in a lock-stitch straight buttonhole sewing machine, it is to be understood that it is not limited to buttonhole sewing machines of this specific type but is applicable generally to sewing machines of the group-stitching type having a work-clamp and a thread-cutter, as defined in the claims. Having thus set forth the nature of the invention, what I claim herein is: V

1. In a sewing machine, the combination with stitch-forming mechanism, a workclamp, means for relatively moving, the

. stitch-forming mechanism and work-clamp to sew a group of stitches, a stop-motion device, a thread-cutting and nipping ClEVICQ adapted to hold the beginning end-of the needle-thread, and means for twice opening and closing said thread-cutting and nipping device for each group-stitching operation, once to release and retrim the beginning end of the needle-threadbefore the-sewing operation .is completed, and again to nip and sever the needle-thread at the completion of the sewing operation. I

2. In a sewing machine, stitch-forming mechanism, a work-clamp, a feed-shaft and connections for relatively moving the stitchforming mechanism and work-clamp to sew a group of stitches, a stop-motion device, a thread-cutting blade, means on the feed shaft. and. connections for actuating the thread-cutting blade to retrim the beginning endof the needle-thread during the sewing, and means connected to be operated by the stop-motion device for operating thethr'eadcutting blade at the end of the sewing period.

3.-.In a sewing machine, in combination, stitch-forming mechanism including a needle, a worlnclamp, a thread cutter mounted on said work-clamp, a stop-motion device, a

feed-shaft and connections for imparting a travellmg movement to the work-clamp,

means actuated by the feed-shaft for operating the thread-cutter during the sewing to retrim the beginning end of theneedle-thread and means connected to be operated by the stop-motion device for again actuating the thread-cutter at the completion of the sewing operation.

4. A buttonhole sewing machine having,

combination, stitch-forming mechanism in eluding a needle, a work-holder, means for relatively moving the stltch-formmg mechanism and work-holder to sew around a buttonhole, a stop-motion device, a thread-cutting and nipping device mounted on the work-holder and comprising an upper nipping element, a lower cutting element and an intermediate movable element cooperating with the upper element to nip the needlethread and with'the lower element to sever the needle-thread, and means for opening 'a work-holder, means for relatively moving the stitch-forming mechanism and work holder to sew a straight buttonhole with barred ends, a thread-cutting and nipping cev'ice, and means for opening and closing. said device after the first end of the buttonhole is barred to release and return the beginning end of the needle-thread, andtor again opening andclosi'ng said device after the second bar is completed to nip and sever the needle-thread. V

6. A straight buttonhole sewing machine having, in combination, lockstitch-forming mechanism including a vibrating needle and shuttle, said mechanism operating to pull loops of the sl1uttle=thread to the upper side of the work' to form a purled lock-stitch seam, a work-holder, means for relatively moving the stitch-forming mechanism and work-holder to sew a straight buttonholewlth barred ends, a thread-cutting device, and means for actuating said device to retrnn the beginning end of the needleithread after the first'bar but before the final bar is sewed and for again actuating said device after the final bar is sewed to sever the needle-thread extending from the needle to the last stitch.

7. in a sewing machine adapted to sew a group of stitches and then come to rest, stitch-forming mechanism, a stop-motion device, a work-clamp, means for imparting a travelling movement to the work-clamp, a thread-cutter carried by said work-clamp,an endwise movable spring-energized rod carried by the work-clamp and connected to actuate said threadcutter, and means for setting and releasing said rod twice per group-stitching cycle of operations. 7

8. In a'sewing machine adapted to sew a group of stitches and then come to rest, stitch-forming -1nechani sm including a sewing shaft, a stop-motion device, a workclamp, means for imparting a travelling movement to the workblamp, a thread-cut ter carried by said work-clamp, an endwise movable rod carried by the worleclamp and adapted to twice open and close said threadcutter per groupstitching' cycle, means connected to the stop-motion device for controlling the thread-cutter closing movement of said red at the close of a group-stitching cycle, means actuated by the sewing shaft for controlling the thread-cutter closing movement-o1"? said rod at an earlier period of the group-stitching vcycle. 1

In testimony whereof, I have signed my name to this specification v ALFRED R. Woon 

